TP53 and neoplasm: However, concerning the RBE values obtained in this study, as a whole, those of the carbon-ion beams and reactor thermal and epithermal neutron beams in Q cells were significantly larger than those in total cells irrespective of p53 status of tumor cells (Table 4), reflecting the finding that Q cells showed significantly and relatively lower sensitivity than did total cells under γ-ray irradiation and under carbon-ion beams or reactor neutron beams, respectively.